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The number of free electrons activated from valence electrons increase, which make excess electrons show up in the bottom of conduction band, and the carrier concentration of the internal crystal increase accordingly.
With the increase of doping content, number of free electrons and carrier density, the conductivity of powder decreases[5-9].
SEM image of Al3+-doped tin oxide gel grains The microstructure and distribution of Al3+-doped ZnO gel grains were shown in Fig.1.
It was found that the grains varied in size from 10 to100nm and evenly distributed during the formation of gel, which revealed that polyethylene glycol (PEG) could effectively prevent ZnO gel grains from agglomerating.
Polyethylene glycol (PEG) could effectively prevent ZnO gel grains from agglomerating during the formation of the gel.

The results showed that the threshold led to a higher number of identified grains with lower mean area and total area fraction than the watershed method.
The grain size can be obtained by drawing a line on the image.
Then, the total number of grains within the line is divided by the length of the line [2].
It is expected a certain difficulty in the selection of a grain, or in this case, all the grains of a phase in the image.
There is a white grain in the center of Figure 6-b, a white line indicates the selected area of the grain using thresholding.

The obvious large grains are interpreted to have recrystallised so as to generate the fine-grained areas, which then deformed superplastically.
Experiments on olivine indicate a regime in which it deforms with a stress exponent ~1 and grain size exponent ~3, indicating grain boundary diffusion creep [15], with equiaxed grains (Fig. 3).
Secondly, grain rotations have been invoked to explain the absence of overall grain shape in superplastic materials.
Our model [5] allowed us to predict grain rotations but for small number of grains where there was a strong influence of the model boundary conditions.
Fig. 5 shows how grain rotations reduce through time, and how grain boundary segments become aligned.

The literature reports a considerable number of research works that deal with grain coarsening problem in FSS welds.
The grain size is measured by IMAGEJ software.
It is observed the presence of large columnar ferrite grains.
It’s observed that the addition of Aluminum (Al) or Titanium (Ti) reducing the grains size and increase the equiaxed grains fraction with varying degrees.
The fracture surface morphology of sample treated by powder mixture (Al+Ti) addition displayed ductile morphology which is characterized by larger number of dimples and pores.

As the tool approaches to the grain boundary, the defects are seen to be accumulated near the grain boundary.
Then, the grain boundary motion is traced.
The initial grain boundary lay in A-A line.
However, the grain boundary bent as B-B line.
Since the number of contact atoms becomes smaller during the lithography than the indentation, the forces summed over the contact atoms are obtained lowest.

of grains” means the number of grains where in GB, NGB, or IG-position is the indent located.
“Number of skipped grains in matrix” means the number of in-matrix-lying grains without indent.
“Maximum number of indent in 1 grain” means the maximum number of indents located in one grain, the indent lies inside the grain.
Number of measured grains increases with increasing distance between indents for the same number of indents, however the number of skipped grains increases and therefore measurement efficiency is decreasing.
Number of inside-grain indents depends on microstructure.

Finally, the hardness values are reasonably homogenous along the disc diameter as the number of turns increases to 5 and 10 turns.
There are some reports on the grain refinement during HPT processing of Al-5% Mg [9] and Al-1% Mg [10].
The grain structures in the HPT-processed Al-0.1% Mg were also examined by EBSD using a JSM6500F SEM.
Fig. 3(a) shows the disc centre area has coarse grain structures but with higher number fractions of low-angle boundaries introduced by HPT shear deformation.
Langdon, Principles of equal-channel angular pressing as a processing tool for grain refinement, Prog.

Abstract.Within the general context of solid-state sintering process, this work presents a numerical modelling approach, at the grain scale, of ceramic grain packing consolidation.
This grain boundary surface tension condition can be written as follows: [σn]gb = γgbκn (21) over the grain boundary Γgb, and has to be added to the mechanical problem (12)-(14).
One of the difficulty of simulating grain boundary diffusion is that we have to consider one level-set function per grain.
As in [6], the simulations presented in this work have been performed by using a mesh adaptation strategy aiming to obtain accurate results while keeping a ``reasonable'' number of mesh elements.
The mesh adaptation strategy used allows to perform simulations while keeping a ``reasonable'' number of nodes and elements and is specially useful when dealing with 3D simulations as the number of mesh element is dramatically increased compared with a 2D simulation.

In a number of studies [4,15–18], twinning was observed at a fist stage of nucleation and continued to develop during the grain growth until the completion of recrystallization.
The number of Σ3-twin boundaries increased greatly (Fig. 3 g-m) to the end of the recrystallization.
The number of special boundaries Σ3 decreased insignificantly and it was due to HAGB between the grains, while the Brandon criterion decreased 5 times.
The role of special boundaries having a large number of coincident sites during recrystallization of FCC metals is described in [6].
Thompson, A comparison of grain boundary evolution during grain growth in fcc metals, Acta Mater. 61 (2013) 3936–3944.

The coarse-grained alumina specimen, TM7, was selected for additional testing, in the hope of analysing the effect of incident wave shaper with regards to strength results.
Influence of grain size on the dynamic response behavior of alumina.
SHPB stress-strain curves for alumina ceramics with different grain sizes It is well known that microstructural inhomogeneities caused during material preparation (e.g. inclusions, grain boundary impurities, secondary phases, porosity, etc.) are the main cause of cracking and can lead to material fracture.
As the applied load increases rapidly, the inertial effect of accelerated crack expansion prevents the initial stage of material fracture from occurring, and microcracks are generated in large numbers but do not converge, the material remains integral at this point and therefore ceramic materials exhibit a high compression strength under high strain loading.
The fine grain alumina ceramic SH3 exhibited a high dynamic compressive strength of 3.80±0.25 GPa, as compared to the SHPB experiments conducted on the alumina ceramic materials.